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Impulse AQ Coil Connector False Signals


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First off, I want to point out that what I am about to describe is not uncommon with high power detectors that have a coil that can be disconnected. The only way to really eliminate the problem is to hard wire the coil, which is another reason for why this option is chosen by so many manufacturers of underwater metal detectors. The White's TDI Beachhunter is a good example. The problem has its root in coil capacitance and the high voltages involved, and the difficulty of getting good shielding using a removable connector.

If the Impulse AQ is submerged halfway, so that the water level is anywhere in roughly the area indicated in the photo below, you will get continuous false signals. Just holding the unit stationary in the water at this level will cause signals as the water moves around the connection area. If you are not aware of what is happening it is every easy to mistake this for electromagnetic interference (EMI).

The problem is worst in the Tones mode, which I just happen to be using a lot. It is accentuated by a short pulse delay, high sensitivity settings, and low ATS settings. If you want to reduce the false signals, here are some solutions:

  1. Use the All Metal or Volcanic modes instead of Tones
  2. Increase the Pulse Delay to 9 or higher
  3. Reduce the Sensitivity to 4 or lower
  4. Increase the ATS to 8 or above

Or some combination of the above.

In practice this only occurs when wading, and only at a certain depth. My solution was simply to stay either deeper or shallower. This does leave a strip or area unhunted. You can either switch the settings as suggested above, or do something to change the height. Like hunt that strip with mask and snorkel, for instance. 

Anyway, hopefully this is put in the manual as it is something inherent in the operation of the detector, and can drive you nuts if you run into it and do not know what is going on. It took me several hours of detecting to put two and two together, and it was then confirmed that yes, that is the way it is.

fisher-impulse-aq-coil-connertor-false-signals.jpg

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I can also see that being a "problem" if waves are intermittently hitting that area. Had it happen to me with an Infinium. As soon as the salt water touched the plug area or if the housing came in contact with my wet trunks it would sound off. Funny thing... it never happened "out of the box" but I sent it in for some repair and when it came back the problem arose. So I sent it back again and it was fixed. I don't know what they did.

I wonder if the AQ will be even worse in the salt water?

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45 minutes ago, okara gold said:

Had it happen to me with an Infinium. As soon as the salt water touched the plug area or if the housing came in contact with my wet trunks it would sound off. Funny thing... it never happened "out of the box" but I sent it in for some repair and when it came back the problem arose. So I sent it back again and it was fixed.

And in the in the thread on Gold ... Class Ring and Medallion

On 6/27/2020 at 2:57 PM, Joe Beechnut OBN said:

"The AQ does have a sensitive area, just like my excalibur with the coil change fitting and the Garrett Infinium LS...... ..right around the coil connector...So in rough or splashing waters your going to hear every little splash (falsing) . I have learned on the excalibur to time my hunting to when the tide will be right below or above. Either the water will be below the sensitive area or above...nothing right at...and now the same goes for the AQ"

So if it can be fixed with the Infinium, can it be fixed with the AQ? I'd like the hear from Alexandre Tartar if it can be worked with an assembly detail fix or something else or if it is something to just live with. The adjustments at least allow some mitigation.

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On 7/8/2020 at 5:36 PM, tvr said:

So if it can be fixed with the Infinium, can it be fixed with the AQ? I'd like the hear from Alexandre Tartar if it can be worked with an assembly detail fix or something else or if it is something to just live with. The adjustments at least allow some mitigation.

The “somebody” I confirmed all this with was Alexandre Tartar, which is why I am posting it here. The setting suggestions are based on his suggestions.

The Infinium is a low power detector by comparison, and also running at a lower pulse delay. So it is already inherently less prone to the issue. It’s worse on the AQ than it was on my several Infiniums.

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I had the same with my Infinium.

There is a wire that is connected the connector to the mother board, Ground ?  cut it , problem solved.

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14 minutes ago, Steve Herschbach said:

The “somebody” I confirmed all this with was Alexandre Tartar, which is why I am posting it here. The setting suggestions are based on his suggestions.

Thank you. And sorry about the mixed bold stuff above ... I fought with trying to quote from different threads in one reply and the tools won.

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I don't mind it, it's something I've adjust my hunting to ... tides make it possible..............one reason I have become a hunter who watch's the current and predicted conditions very close..

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Certainly good to know- thanks Steve. 

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9 minutes ago, Joe Beechnut OBN said:

I don't mind it, it is something I adjust my hunting to having... tides..............one reason I have become a hunter who watch's the current and predicted conditions very close

Agreed. And a little lol ... part of what the "tools won" trying to quote two threads in one is that after three tries, I shortened my reply and did not put in the part where it wouldn't change how useful the AQ could be, just a minor tweek in use methods.

Heck, the SandShark was dead quiet with a connector on the coil, but the much noisier HHPu;se (with the coil connector on the headphones that only got dunked when I got rolled by a wave) was a better gold producer by far and much easier to figure iron once I found ways to have more listen time around the noise creating wave and water depth events.

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7 hours ago, Steve Herschbach said:

First off, I want to point out that what I am about to describe is not uncommon with high power detectors that have a coil that can be disconnected. The only way to really eliminate the problem is to hard wire the coil, which is another reason for why this option is chosen by so many manufacturers of underwater metal detectors. The White's TDI Beachhunter is a good example. The problem has its root in coil capacitance and the high voltages involved, and the difficulty of getting good shielding using a removable connector.

If the Impulse AQ is submerged halfway, so that the water level is anywhere in roughly the area indicated in the photo below, you will get continuous false signals. Just holding the unit stationary in the water at this level will cause signals as the water moves around the connection area. If you are not aware of what is happening it is every easy to mistake this for electromagnetic interference (EMI).

The problem is worst in the Tones mode, which I just happen to be using a lot. It is accentuated by a short pulse delay, high sensitivity settings, and low ATS settings. If you want to reduce the false signals, here are some solutions:

  1. Use the All Metal or Volcanic modes instead of Tones
  2. Increase the Pulse Delay to 9 or higher
  3. Reduce the Sensitivity to 4 or lower
  4. Increase the ATS to 8 or above

Or some combination of the above.

In practice this only occurs when wading, and only at a certain depth. My solution was simply to stay either deeper or shallower. This does leave a strip or area unhunted. You can either switch the settings as suggested above, or do something to change the height. Like hunt that strip with mask and snorkel, for instance. 

Anyway, hopefully this is put in the manual as it is something inherent in the operation of the detector, and can drive you nuts if you run into it and do not know what is going on. It took me several hours of detecting to put two and two together, and it was then confirmed that yes, that is the way it is.

fisher-impulse-aq-coil-connertor-false-signals.jpg

The high voltage and short pulse delay of the Impulse are requiring a strict shielding of all the parts subjected to the pulses (coil, cable and connector).

That effect is due to the small gap of continuity of the cable shield between the the male and female connectors and the changes of capacitance coming from the conductive  water level variations.

It was for that reason that the coil connector was initially made of metal in order to keep the continuity of the cable shielding up to the inside of the enclosure. (Same supplier, other item)

Field tests in the sea water had shown a bad electrolysis effect on its body giving it a nasty look.

A plastic connector had to be used for the AQ.

The GOLD version will even require more attention to this capacitance effect as it will have a much  shorter pulse delay, it will get an (expensive) stainless steel connector to keep a perfect shielding.

 

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